Basic methods of PCB assembly: THM & SMT

Q: Basic methods of PCB assembly: THM & SMT

W hen it comes to the PCB assembly, there are two type of components that can be placed on a printed circuit board (PCB). The first one is Through-Hole Mounting (THM) and the Surface Mount Technology (SMT). You can make a decision on which one to use, even more, you can use both two of it on your designed PCB. Double-sided reflow requires two reflows, and have you ever wondered which side should pass through the reflow oven first? In general, the side with small components on it will pass through first. First of all, because the first reflow will not cause too much deformation to the PCB, the solder paste printing is relatively accurate, and the probability of small parts dislocation is small. Secondly, during the second reflow, the small components are facing up and will not come off due to the high temperature and gravity. Both methods have its Pros & Cons. We will go through this topic in the future articles.

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Accepted Answer

When it comes to the PCB assembly, there are two type of components that can be placed on a printed circuit board (PCB). The first one is Through-Hole Mounting (THM) and the Surface Mount Technology (SMT). You can make a decision on which one to use, even more, you can use both two of it on your designed PCB.

Double-sided reflow requires two reflows, and have you ever wondered which side should pass through the reflow oven first? In general, the side with small components on it will pass through first. First of all, because the first reflow will not cause too much deformation to the PCB, the solder paste printing is relatively accurate, and the probability of small parts dislocation is small. Secondly, during the second reflow, the small components are facing up and will not come off due to the high temperature and gravity.

Both methods have its Pros & Cons. We will go through this topic in the future articles.